Paxman in the Early 1890s
The following is the text of an article about Davey, Paxman and Co which appeared in 'A Descriptive Account of Colchester - Illustrated', published in 1893. It gives a detailed description of the Company's premises at the time, the machinery and processes used, and some of the products manufactured.
The text is reproduced here without any amendment or editing. The illustrations referred to were engravings which have not been reproduced as they are not of good quality in the source photocopy.
The last page of the article was a full-page Davey, Paxman & Co. advertisement, carrying brief details of a wide range of products made by the Company at the time.
MESSRS. DAVEY, PAXMAN & CO.,
Engineers, The "Standard Iron Works."
The "Standard Iron Works," situate at Hythe Hill, and the inventions and productions of Messrs. Paxman, are of world-wide fame, and the excellence, durability, and high-class finish of the boiler engines and other machinery made there have gained the highest awards at numerous exhibitions in all parts of the world since 1865, and have been accorded the direct patronage of Her Most Gracious Majesty the Queen, other members of the royal family, and the Home, Indian, Colonial and many Foreign Governments. During our visit to Colchester we were given cordial permission to visit the works. Though necessarily of very superficial character, we trust that our relation of what we saw, and of the many interesting processes employed, may prove acceptable to our readers. Rather more than twenty-five years ago these magnificent works were erected to accommodate the business established by Messrs. Davey and Paxman in 1865. In 1878, Messrs. Daveys retired, and today the firm of which Mr. James Paxman is the sole proprietor ranks as one of the largest in the Kingdom. The business is by far the most important in Essex. The shops and works, which are most solidly and substantially built in red brick and stone, occupy an area of eleven acres on a dry and healthy situation, and are most complete in their equipment of plant and modern machinery. By the employment of the most intelligent description of skilled labour under personal direction and use of the best obtainable material, the proprietors have obtained a reputation which is universally acknowledged, and made the name of Paxman synonymous with engine building success. The situation of the works is, in the estimation of the proprietors, one of the best in England for manufacturing purposes, since it is close to London and convenient to rail and water carriage, the latter of which, from the north, is very cheap. The whole of the management devolves upon Mr. Paxman, assisted by his son and an able staff; but by an organized methodical system he is enabled to supervise the minutest details throughout the business personally; no doubt the unqualified success achieved may, in a great measure, be attributable to this fact, and also because every particle of work is done on the premises, from the designs and drawings to the polishing and ornamental finishing touches. The chief output from these works comprise from 1-h.p. to 2,000-h.p. steam engines and boilers, suitable for all kinds of purposes, and for electric light installations, mining machinery, portable, semi-portable, fixed, semi-fixed, vertical, simple, and compound; winding and hauling engines, and all descriptions of boilers, specially designed to meet the requirements of engineers, electricians, contractors, mining companies and others. There are about 260 sets of patterns of different varieties, and these are being constantly added to. For excellence of design and perfect workmanship and efficiency, the united opinion of the most competent judges is, that they cannot be surpassed. Among the many large public and private installations put down by the firm should be mentioned the group of compound condensing steam engines with compressors and battery of boilers for the Compagnie de l'Air Comprimé Systèmme Popp, at St Fargeau, Paris; and the great International and other exhibitions held during the past few years, including the Fisheries, Health, Inventions, Colonial, Italian, Royal Military, Royal Naval, The Mining, French, German, Electrical, and "Venice in London," all in London. The Manchester Jubilee, the Mining and Industrial, Newcastle-on-Tyne, and the Paris Universal of 1889, besides many others at home and abroad. When it is borne in mind that the above exhibitions were mainly and in many cases entirely dependent upon this firm's engines, the steady running of the machinery for the illumination of the courts and gardens, and that during the whole of the periods Messrs. Davey, Paxman and Co.'s engines did not in one single instance fail in their duty, it is unnecessary to say more regarding their perfection.
The offices, situated at the entrance to the works, are of two floors, and comprise gate and timekeeper's lodge, reception rooms, general counting house, manager's office, proprietor's rooms, and spacious drawing offices with admirable north light. All these are handsomely fitted and furnished in a manner suitable to their requirements. These, as well as the yards, are illuminated by electric light. In the reception rooms we were interested in the vast collection of framed diplomas and awards, many of them honoris causa, or for "services rendered," while those accompanying gold medals are from all exhibitions and countries where the productions of the firm have been shown. We have cause for thinking that those most highly prized were obtained by the wonderful success of the firm's engines at the Royal Agricultural Society's show at Newcastle-on-Tyne, 1887, (especially as the most extraordinary efforts were made in the first instance to prevent these trials from taking place, and persistent efforts were afterwards made to cast a doubt on the finding of the judges), and that containing the confirmation of the decision by the Society of Arts Trials in 1888, which fully proved the correctness of the Newcastle decision. Paris, Philadelphia, Sydney, Calcutta, Amsterdam, Tasmania, Austria, Sweden and Chili subscribe gold and silver medals, the whole forming a valuable collection and an enviable record of success. After the drawing offices, where some dozen draughtsmen were at work, we visited the boiler house, and found that two boilers, one of the firm's "Economic" type, and a water tube boiler of special construction, were the agents for generating steam for the different engines employed. This house was a pattern of cleanliness and order, and the same remark was applicable to the keeping of each engine and machine throughout the works. Crossing the yard we come to the modelling and pattern department. This consists of three bays, each of which are between thirty and forty yards long and ten yards wide, and are excellently sky-lighted. The patterns, which are of course in wood, are made and finished in a most complete manner by a large staff, assisted by saws, lathes, and planing machines driven by steam power. They vary for types of engines from 1 h.p. to 2,000 h.p., besides other sorts of machines; for instance, we noticed a pattern for a Huntington centrifugal roller quartz crushing mill intended to supplant, and fast superseding, the old-fashioned stamp mills. The action is that the mill being fed through a hopper with ore and water, the interior rotating rollers and scrapers throw the ore against the ring-die, where it is crushed by centrifugal force of the rollers. The pulverized ore and water is thrown through screens, and leaves the pulp in good condition for concentration. The rollers are so accurately fitted that while they pass freely over the quicksilver and amalgam without grinding, while it agitates it sufficiently to make amalgamation perfect, it is said that for wet crushing and gold saving to have no equal, while its cost is less than a stamp battery. The patterns already made occupy a vast space, and are methodically arranged and catalogued, so that parts of, or whole machines are readily obtainable. The adjacent workshop is called the sawing shed, and is exclusively used for the making of packing-cases by a staff of carpenters and joiners; it is about 80 feet long by 30 feet wide. Coming into the yards we notice the large quantities of parts of machinery in stock, in readiness for immediate delivery; it is necessary to maintain this stock to meet urgent demands in case of breakdowns. Although such calls are few and far between, this preparation for emergencies is characteristic of the firm's foresight. The foundry, which may be called the birthplace of all the cast ironwork used, claims our next attention, and its imposing size, viz., 130 feet by 135 feet divided in three equal sized bays, and where between 90 and 100 workmen are employed, impresses the visitor with the important character of the works, especially when it is remembered that nothing is cast here except what is used in the firm's productions. Huge cylinders, immense fly-wheels, engine beds of large size and many tons weight are cast, and these heavy masses are easily lifted and transferred from one part of the foundry to another in a quite surprising manner by the means of overhead steam travelling cranes, capable of lifting 25 tons. For assistance with smaller weights there are jib cranes conveniently placed in different parts, and a tramway with turntables are available for moving weights to fettling department or drying stoves. There are ample stores of mould frames, boxes, cores, and hundreds of tons of pig, scrap, and other iron used in castings, stored in the adjacent yard, where are also many tons of coal and coke. The furnaces are fitted with powerful blast apparatus, and the core drying stores are of suitable size and construction. The noise warns us we are now entering the boiler shop. In this magnificent shed, 400 feet long, of two bays, each about 45 feet wide, we view the construction of many types and classes of boilers from 8 to 250 horse power; the lifting machinery is similar to those in the foundry, but what chiefly attracts us is the hydraulic machinery used for rivetting, pressing, and flanging. The introduction of the rivetting machines has produced quite a revolution in the process. The rivet is brought direct from the heating furnace and placed in the hole, the machine is adjusted, and the rivet pressed into position like a piece of putty, the process being cleanly finished. All holes in boilers are drilled with the plates in position; the drills used are of twist type and admirably effective, and secure much greater accuracy than by punching. The presses for shaping plates with its compound rams and double action, and those for planing the plate edges and shearing, are likewise expeditious and labour saving. Another attractive portion is that of the new boiler welding department, a fine large shed lately added; a portion of this is occupied by the flue flanging department, which is a speciality requiring more than a passing notice. These flues are denominated "Paxman's patent expansion boiler flue," for Cornish, Lancashire or other boilers. They are made up of a series of short lengths composed of fine, soft and exceedingly tough steel, specially made for the firm, or of good iron, at option. The plates are bent perfectly cylindrical, thus adding to strength of flue, and then carefully welded on special anvils, assisted by a steam hammer. The ends are then heated and enlarged by a powerful flanging machine, so that the end of one plate exactly fits within that of the next, the holes are then drilled through both, and the work is completed by rivetting. By this process both the laps, as well as the rivet heads, are removed from the line of draught, and escape the scouring and intense heat as the gases pass along the flue, and the collapsing strength is trebled. Other excellent machines are those for cutting-out oval-shaped manholes, and turning-up dished edges of plates, Boiler shell drilling machines, etc. We visited the large shed, which was originally the court for the exhibit of the firm's machinery at the Paris Exhibition, now used for finished parts store. It is of considerable dimensions, and of lattice and girder structure, well sky-lighted. There are numerous divisions, all numbered and lettered, and like the pattern store, accurately catalogued so that the storekeeper is at once able to procure any portion or class of part required. We inspected the large "Colchester" type horizontal compound steam engine employed to drive the plant, other than hydraulic, in the boiler shops and smithy; and our attention was attracted to the Governor attached; to describe it technically at length would take up more space than is at our disposal, but we can say from enquiries, and expressed opinions, that "Paxman's patent automatic expansion gear and adjustable governor" is one of the greatest modern improvements effected in the steam engine. As a proof of this it is officially recorded that:- "At the Health Exhibition in London, 1884, while one of Davey, Paxman and Co.'s engines was indicating 350 horse power, the main driving belt broke, setting the engine absolutely free, but the governor at once took charge of the engine, and no variation in the speed was perceptible." This happened on two occasions. The smithy is doubtless the best arranged we have had the pleasure of seeing, it is 170 feet long by 45 feet wide, and contains steam hammers, blowers, punching and shearing machines, drilling and screwing machines, and all sorts of appliances for expediting work. There are a number of central double-fitted forges and other heating fires, travelling cranes, large plate tables, and numerous tools. An agreeable temperature is maintained in spite of the number of fires, and it is well-lighted and kept clean and in good order. Leaving here we proceed to the iron and brass turnery. It is about 40 yards long, and is divided into three bays each, each 45 feet wide; in a double gallery the small parts are finished by a smaller and more delicate type of lathes and other tools, some 30 or 40 in number. The ground floor of this building is absolutely full of all kinds of labour-saving machinery and special tools for altering the shape and converting and finishing the materials used in construction of engines and parts of various work. Stupendous lathes, planing machines, and powerful radial drills, boring, milling, screwing, slotting, facing, wheel-tooth making, shaping, shearing, profiling, and numerous other special tools are at full work here. The plant in these shops is driven by one of the firm's "Windsor" type vertical compound engines. It performs its work most admirably. Notwithstanding the perfect labyrinth of wheels, shafting, and belting, and the presence of such numerous machines in rapid motion, there is here, as elsewhere throughout the works, a remarkable absence of vibration, everything working in a perfectly smooth, even manner. Before leaving this building we were shown a special tool in operation for turning the "dips" of crank shafts without swinging them, which gives perfect surface accuracy, as it is impossible to get the great accuracy D. P. & Co. require if the shaft is permitted to revolve. There are suitable overhead travelling cranes and other conveniences for transporting and readily handling heavy weights. At the end of these shops is one of the finest erecting shops in Great Britain. It has a clear width space of 70 feet without a break, and is upwards of 150 feet long, and proportionately lofty. The huge travelling crane, one of the most powerful made, lifts great weights. This building is splendidly lighted. On the occasion of our visit great activity prevailed, and we were informed that this was the normal state of the works, overtime being the rule rather than the exception. It seldom happens that the firm has less than 400 tons of boiler orders on their books with the equivalent engines and gear, so that a regular flow of work is maintained. We saw large consignments of Colchester type engines and appurtenances being fitted for New Zealand; an immense newly-invented "Digger," and numbers of Portable Windsor, Undertyped gear winding, Hauling, Vertical engines were approaching completion, or being taken to pieces. The final testing is a most exhaustive and searching one under power and inspection. In this erecting shop a number of pits are arranged in the floor for the purpose of allowing the fly-wheel to swing. The largest pit will take a fly-wheel 40ft. in diameter, the other pits varying in size. At the side of these pits, cast iron slotted plates are embedded in the concrete on which the engines for trial are secured. In this shop we saw in hand a large number of steam engines (some of them very powerful and of all sizes, ranging from 4 to 500 horse power), many of which were on order for different parts of the world, and the balance for the home markets. The engines and boilers we saw in progress were absolutely on order, and considering the large quantity and variety of steam engines and boilers which Davey, Paxman and Co. are constantly turning out, it seemed to us a marvel how a market could be found for the number; especially when we are informed that Davey, Paxman and Co. do not employ a single traveller, the high character of their work being such as to command a regular stream of work. The "orders" here receive the closest scrutiny by the proprietor, the most minute alterations being made, and the machine re-tested when necessary. Messrs. Paxman are in the enviable position of having above the average supply of orders for some time to come. Leading from the fitting shop are the warehouses and stores. The building is fitted up in such a manner that all the different parts of steam engines and fittings for boilers can be stored away. A list is kept so that within a minute's notice any part can be found and sent into the shop where it is required. From this building we proceed into the small stores where all small brass fittings and tools used by the workmen, such as files, hammers, chisels, bolts, nuts, studs, washers, pins, &c., in fact anything that is required for finishing off engines and supplying men with the necessary tools for the erection of engines can be found in this store. Underneath this store is a fireproof cellar, where large quantities of oil and waste are kept, and also tons of copper and tin. Adjoining the stores are the general offices, which are commodious and well-lighted. All the offices and stores are lit up by electricity. The completeness in supervision, together with excellent design and high quality of materials used, with strict accuracy in every detail, is no doubt the main factor in the success which attends the firm's productions. It is also notable that nearly all the heads of departments and foremen have been in the firm's service a very long time, one having been connected with Mr. Paxman 35 years, and others running him close. That a like unity may exist, and similar triumphs attend in the future as in the past, the efforts of employers and employed alike, is a wish that will be cordially echoed by all who have any business dealings with the firm, or have used the machinery constructed at the Standard Iron Works. Mr. Paxman's career has been one of continual progress. He is not one of those who can rest and be thankful, but is ever on the alert. It is well known in the trade that at engine trials he is one of the most severe competitors, and his great experience and sound practical knowledge of the requirements of steam generators and steam engines is second to none. To-day, the firm ranks as one of the very first order. As proof of his popularity in his native town, we may add that he had the honour of being unanimously elected by both political parties - a precedent unknown before in the borough - as Mayor in 1888. He is an Alderman and J.P. for the borough, and, amongst the many other services to the town, to his successful efforts are due the permanent establishing of the Albert School of Science and Art in Colchester. In recognition of the spirited manner in which he conducted his year of office as Chief Magistrate of Colchester he was presented with a solid silver dessert service, weighing about 170oz., suitably inscribed, together with an illuminated address containing the signatures of the subscribers. The occasion was also taken advantage of to present to Miss Paxman, who so admirably assisted her father as Mayoress, a very handsome cluster diamond bracelet mounted in fine gold. The movement was entirely free from all party bias, and it was very favourably taken, all classes agreeing that Mr. Paxman was thoroughly deserving of the compliment.
THE "ESSEX" PATENT VERTICAL BOILER.
Probably no type of steam generator is so susceptible of variety of design, or is at present to be found in such a diversity of internal arrangement, as in the vertical boiler. Nor is this to be wondered at. Easily moved about, occupying little space, needing no brick setting, and if properly designed, capable of sustaining considerable pressures with safety, it is a most useful type. Until however the year 1870, when Messrs. Davey, Paxman and Co. created a sensation at the Royal Agricultural Society's Show at Oxford, by the extraordinary performances of a vertical boiler, exhibited for the first time there by them, little attention was given to its improvement, and it deserved and received little use. Messrs. Davey, Paxman and Co. then demonstrated to the engineering world that it was just as practicable to make a good evaporating steam producing vertical boiler as of any other type, and they claim with justice that no better one has since been produced, whether as regards evaporative powers, simplicity of construction, ease of working, or durability. They introduced the water tubes descending from the top of the firebox, some distance towards the fire, and turning off to and secured in the sides of the box. The earlier forms of the vertical boiler was nothing more really than a short Lancashire boiler set up on end, and part of the internal flue above the fire contracted in diameter, while succeeding designs did away with a single upcast flue, substituting instead thereof a number of tubes, in either case but a very small portion of this heating surface being covered with water; the remainder therefore was useless as a steam generator. Time changes all things, and the vertical boiler of the present day may be found in many kinds of design. Many points have to be considered in designing a good vertical boiler, and here, as in sundry other engineering subjects, mere high theory travels not always with practical exigency, and in such case the former must of necessity give place to the latter. Thus in theory the heated gases should impinge upon or travel over metallic surface till nearly all their contained heat shall have been absorbed by the water at the other side of the plate, only heat enough being left in the gases to maintain efficient draught in the uptake; and probably spiral tubes, or those bent and twisted in fantastical shapes, by incessantly deflecting the hot gas currents, would be most efficient for this: but practical considerations of keeping the tubes swept, easily removing defective or worn out tubes, perfect accessibility to all parts, non-liability to get out of repair, and power to effect repairs cheaply and rapidly - all these are matters quite as important as great evaporative efficiency. Boilers which may be designated "racers" can be made; they will under racing conditions give high evaporative results. As many as eleven or even more pounds of water, evaporated by a pound of good steam coal, have been claimed, but such boilers are not suited for constant daily duty, and are not therefore much sought after. The steam generator most useful is that which, while giving a good evaporation, will work all the year round without needing especial care and highly skilled attendance, can be made and sold to steam users at a reasonable price, and whose maintenance cost shall be low. Messrs. Davey, Paxman and Co.'s new "Essex" Patent Vertical Boiler, as here illustrated, may fairly claim to comply with the conditions above enumerated. It may be described as follows:- A straight neck, secured to the top of firebox, conveys the products of combustion into a chamber to the left. This chamber is of a triangular shape, and has an outer flange, by which it is rivetted to the shell of the boiler, and to which a door is fitted. An exactly similar chamber is in like manner secured at the right side, with a door and uptake constituting a smoke-box. These two chambers have a number of tubes of a somewhat semicircular shape uniting them. The curves of the tubes being of a greater radius than that of the boiler, enables them to be easily put in or withdrawn. The chambers are made of a special mild quality of steel, very ductile and easy to weld. It is manufactured for Davey, Paxman and Co., and each plate is carefully annealed after having passed through the various machines. The chambers are formed, while hot, in a special hydraulic pressing machine, and are then annealed, so that all the best qualities of the steel are preserved. The shape of the flues causes a centrifugal action in the hot gases, which brings every portion of them into direct contact with the tube surface, so that the highest efficiency is obtained from the heating surface, while, at the same time, full circulation of the water is secured. The boiler is made entirely of steel, and will be found an excellent one for land purposes, as well as for steam launches, etc., as it can be made so as to occupy very little space, and at the same time contain a large amount of heating surface. These "Essex" boilers produce dry steam, and as they possess all the essential features of the best type of boilers they can be strongly recommended. They are without exception the best and most economical vertical boiler in the market, when efficiency and heating surface are taken into consideration. Each boiler is tested by hydraulic pressure to double its working pressure before leaving Davey, Paxman and Co.'s Works. Their present large and constantly increasing boiler trade is a conclusive proof of the high estimation in which their work is held, and of the excellent materials and high-class workmanship employed in the manufacture of their boilers. The requirements and circumstances of each particular case are carefully studied, and the long and varied practical experience which Davey, Paxman and Co. have had in the manufacture of boilers of every description, enables them to give the best advice in the selection of a boiler so as to ensure the maximum of efficiency and economy.
IMPROVED HORIZONTAL COUPLED COMPOUND GIRDER STEAM ENGINE.
This illustration represents one of Davey, Paxman and Co.'s improved horizontal coupled compound girder steam engines. These engines are made in all sizes from 8 h.p. to 1,000 h.p. and upwards. As will be noticed from the illustration, one crankshaft connects the two engines, and the fly-wheel is placed in the centre. The cylinders are made of a hard and specially good mixture of close grained cast-iron. The front cylinder cover, crosshead guide main bearing for crankshaft, and foot for bolting to foundation, are cast in one piece, to which the cylinder, with valve chest, is bolted. The engines are placed side by side, and in such a manner that the high pressure engine is on the right-hand side, and the low pressure engine on the left hand side, when standing at the cylinder end and looking towards crankshaft. The cylinders are jacketed, the jacket being formed by an inner liner, which is cast separately, accurately turned and bored and forced into the outer cylinder. The piston is of Davey, Paxman and Co.'s improved construction, and the piston and slide-rods are of steel. The crankshaft is made of steel, and a heavy cast-iron turned and polished disc is forced on to each end by special machinery. Each disc is fitted with a steel crank pin. The fly-wheel is extra large and of ample weight, and may be made with flat rim, to take a driving band as shown, or with grooved rim for rope driving. All the wearing surfaces of the engines are very large to allow long runs to be made without stopping, and ample means for lubricating are provided for this purpose. The high pressure cylinder is fitted with Paxman's patent automatic expansion gear, consisting of two slide valves, one main and one cut-off, the latter deriving its motion from a link, each end of which is connected to one eccentric, the two eccentrics having a different travel. The results given by this gear are equal to those obtained by the best Corliss or tappet valve motions, while at the same time it is most simple and durable, the diagrams being excellent. With this gear the point of cutting off steam is varied automatically, as required, from 0 to 5/8 of the stroke, thus ensuring great economy in the consumption of fuel and steam, as only the exact amount of steam required to do the work at each stroke of the piston is admitted to the cylinder. The governor is of Davey, Paxman and Co.'s new and improved adjustable high speed type, keeping the engine under good control. A condenser is strongly recommended to be attached to the engine when water is easily obtainable. These engines are made for a working pressure of 80lbs. per square inch and upwards, and the workmanship and materials throughout are of the very best description. This class of engine is also made as a single tandem compound, i.e., with the low pressure cylinder behind, and in a line with the high pressure cylinder, one connecting rod serving for both. It is also made as a coupled tandem compound engine, i.e., two single tandems coupled together with one crankshaft and fly-wheel common to both. Davey, Paxman and Co. erected at St. Fargeau, Paris, a battery of their horizontal coupled compound girder steam engines, with air compressors, developing about 4,000 h.p., for distributing air through the streets of Paris for driving prime movers.
IMPROVED UNDERTYPE COMPOUND ENGINE AND BOILER COMBINED.
This illustration shows one of Davey, Paxman and Co.'s improved undertype compound engines and boilers combined receiver type. The smaller sizes of this type of engine, viz., from eight to twenty horse power inclusive, are built on a strong and neatly-designed cast-iron bedplate, and are self-contained. But in the larger sizes, from 25 horse power upwards, the engines are built on a cast-iron girder frame, consisting of several parts bolted together, which greatly facilitates transport and repairs. These engines are constructed on the same principle as the compound portable engine made by Davey, Paxman and Co., and which, after competitive trial, open to all makers, took the only prize (£200) offered by the Royal Agricultural Society of England, at their Newcastle-upon-Tyne meeting in July, 1887, for the best compound portable engine. Davey, Paxman and Co. were at the same time and place awarded the only prize (£100) for the best single-cylinder portable engine. These awards were given for great efficiency, extreme economy in fuel and steam, and the general excellence in design and workmanship, the judges in their report saying:- "The trial of this (compound) engine was characterised by perfect smoothness of working and great regularity of speed, the governor having perfect control of the engine." The cylinders are placed side by side, and each is provided with a separate steam chest and slide valve. They are made of a hard and specially good mixture of close grained cast iron, and are so proportioned that the duty is about equally divided between each when the engine is doing its fair load. Each cylinder is jacketted, the jacket being formed by forcing a truly turned and bored bush into the outer cylinder. The connecting rods are fitted on the most approved principle and are of new design and very strong. The piston and valve rods are of steel, finished bright, and the crosshead is of Davey, Paxman and Co.'s improved pattern. The crankshaft is of mild steel and sufficiently long to take the flywheel on either or both sides of the engine. In the larger sizes the cranks are slotted and a counter-balance disc is forced on the shaft. This greatly enhances the beauty and finish of the engine. The high pressure cylinder is fitted with Paxman's patent automatic expansion gear controlled directly by the governors, and its action is as efficient as that of the Corliss valve gear, with the conspicuous advantage over it that a large number of tappets and the multiplicity of levers, rods, and joints are dispensed with. This gear consists of two slide valves - one main and one cut-off - the latter deriving its motion from a link, each end of which is connected to one eccentric, the two eccentrics having a different travel. With this gear the point of cut-off is varied automatically, as required from 0 to 5/8 of the stroke, thus ensuring great economy in the consumption of fuel and steam, as only the exact amount of steam required to do the work at each stroke of the piston is admitted to the cylinder. The engine is so constructed that it may be started in almost any position of the cranks by means of a small valve, which opens communication between the high and low pressure steam chests. All wearing surfaces are very large to allow the engines to run for long periods without stopping, and ample means for lubricating are provided for the purpose. The boilers are made in the best locomotive style, entirely of steel, with flush top. They are thoroughly well stayed throughout and the most modern and improved machinery, including flanging, pressing, and rivetting machines, plate-edge planing and drilling machines, special machinery for cutting out oval manholes, and turning up the dished edges of plates, boiler shell drilling machines, etc., are employed in their manufacture. The fireboxes are made of very mild steel, almost as ductile as copper, or of low moor, bowling, or other best Yorkshire iron, at the option of the purchaser; but from the long experience Davey, Paxman and Co. have had in the use of this special steel, they feel justified in recommending it in preference to the best iron. The tubes are inserted in the boilers on an improved method, which renders them more durable and less liable to leakage, and the use of ferrules is entirely dispensed with. The whole of the fittings and mountings are of the best quality throughout. Each boiler is lagged and cased the whole length with silicate cotton, wood and steel iron, with the exception of the smoke-box, and is neatly painted, lined out, and varnished. Condenser and air-pump can be applied when required, and where water is plentiful and easily obtainable, it is recommended to reduce the cost of fuel consumption to the lowest possible figure. Engines of this type are now working in various parts of the world, and giving the most complete satisfaction. They embody many very important improvements, and are especially well suited for large electric light installations, as well as for driving mills, manufactories, pumping, and other machinery. For excellence of material, good design, solidity of construction, durability, economy, and perfect running, these engines are not surpassed. Davey, Paxman and Co. make compound engines in all sizes from 8 to 150 horse power nominal, and their very large experience enables them to give the best advice as to which sizes and types of engines, boilers, &c., to adopt to ensure the maxims of efficiency and economy in each particular case.
IMPROVED COMPOUND PORTABLE STEAM ENGINE.
Davey, Paxman and Co. have given unremitting attention to the construction of non-condensing compound engines, and the splendid results their engines have obtained are widely known. Other makers have had to follow their example, and compound engines are now universally adopted for all kinds of work. Davey, Paxman and Co.'s improved compound portable engine is of the receiver type, the cranks being at right angles. The two cylinders (i.e. the high and low pressure) are made in one casting, and each cylinder is jacketed, the jacket being formed by forcing a truly turned and bored liner into the outer cylinder. The high pressure cylinder is fitted with Paxman's patent automatic expansion gear, worked direct by Paxman's patent adjustable high speed governor. This excellent expansion gear is without doubt the best and most reliable in the market, and is certainly one of the greatest modern improvements effected in the steam engine. With this gear the point of cut-off is varied automatically, as required, from 0 to 5/8 of the stroke, thus ensuring great economy in the consumption of fuel and steam, as only the exact amount of steam required to do the work at each stroke of the piston is admitted to the cylinder. The engine is mounted in a strong wrought channel iron frame, and is, so to speak, independent of the boiler. It is attached by eight bolts to four wrought iron brackets rivetted to the boiler, so that, on removal of the eight bolts, the engine can be completely detached. Davey, Paxman and Co. consider that, for high pressures, the boiler should be relieved from undue strains. A most efficient feed water heater is provided, a portion of the exhaust steam meets the superfluous water and warms it. The crankshaft, connecting rods, piston rods, and crossheads are of steel. The boiler is of the locomotive type, with flush top. It is double rivetted in the longitudinal seams, and made in the best possible manner. The holes are drilled, and the best home-made rivets used, and the edges of all plates planed. The fire-box is made of specially mild ductile steel, which is expressly manufactured for Davey, Paxman and Co. This steel is remarkably ductile and easy to weld. We are informed that Davey, Paxman and Co. have for many years used this steel for fire-boxes, and the results have been most satisfactory. Each plate is carefully annealed after having passed through the various machines. The steel fire-boxes enhance immensely the value of the boiler, as it adds greatly to its life. Davey, Paxman and Co. have found that up to the present these fire-boxes may be safely relied upon to do double the duty of the very best brands of Yorkshire iron. This achievement has not been brought about without considerable trouble and numerous experiments. The fire-box is well stayed to the shell by screw stays, and the crown is supported by roof and sling stays, and connected to top of boiler in the best locomotive practice. The engine is well finished in every respect, all wearing surfaces are very large, and, as will be seen, the general design of the engine is most excellent.
TRIPLE EXPANSION "WINDSOR" VERTICAL ENGINE WITH DYNAMO COMBINED.
This engine has been designed and introduced by Davey, Paxman & Co., to supply the constantly increasing demand for a type of motor which will give considerable power in a very small space, be inexpensive to work or keep in order, and run at perfectly uniform speeds for long periods without a stoppage. The great development of electric lighting has created a special need for such an engine in cases where it is of great importance either to couple the dynamo to the prime mover direct, or to have as small a difference between the speeds of the two as possible. The design has been most carefully studied to meet the requirements of electric light installations, and no expense has been spared to produce the most economical, serviceable, and durable engine for the purpose. The "Windsor" is in every way a very superior and highly finished engine, and cannot be compared with the ordinary type of vertical engine. All the wearing surfaces are very large, to allow the engines to be worked for many hours without stopping, and special means of lubrication are provided to enable the engines to run for many months without adjustment. The cylinders are made of a hard and specially good mixture of close-grained cast iron, bored out true and parallel, and are so proportioned that the work done is about equally divided between each when the engines are doing their load. They are placed side by side, each being provided with a separate steam chest and slide valve, and are mounted on the top of strong cast iron back standards, and supported by steel columns in the front. Paxman's patent automatic expansion gear is fitted to the high pressure cylinder, and is controlled directly by the governor. The automatic valve derives its motion from a link, the ends of which are connected to eccentrics of different travels, and different angles of advance, one giving a late and the other a very early cut-off. The governor, which is of Paxman's improved design, and extremely sensitive in action, controls the stroke of the link, thus determining the amount of steam admitted to the cylinders, and keeping the engine under absolute control. The cut-off valve moves on a ported plate, which lying upon the main valve, loosely fits the steam chest, and the ports themselves are tripled, thus reducing to one third the travel of the cut-off slide, and increasing the sensitiveness of the governor's control. The advantage of this arrangement is that, while a constant lead is maintained, the point of cut-off can be varied to any degree without wire-drawing the steam. A steam pipe connection is fitted between the high and intermediate steam chests, with a small wheel valve, so that if the cranks are not in a favourable position at starting for steam to act on the high pressure piston, live steam can be admitted into the intermediate steam chest, and the engine started from any position. The crank shaft is of mild steel with slotted cranks, and runs in four long bearings; the piston rods, crossheads and slippers, are forged from one piece of steel, and the connecting rods are of the best forged iron of marine engine pattern, the small end being forked, and a steel crosshead pin firmly shrunk into the eyes. The main bearings and big end brasses are of white metal, with adjustable liners. The engraving on page 24 is taken from the photograph of a triple expansion engine of the Windsor type, which was employed at the Crystal Palace Electrical Exhibition, 1892, to drive direct a multipolar dynamo, having an output of 145 kilo-watts. This, the most powerful one to be seen in the Exhibition, was designed for a working pressure of 160lbs., and to indicate 350 horse power, running at a speed of 140 revolutions per minute. No expense is spared in the workmanship and finish of these engines, and the materials employed in the manufacture of the various parts are specially selected for the purpose, and are of the very highest quality.
The illustration on page 25 represents a group of horizontal coupled compound girder, receiver type steam engines, provided with horizontal jet condensers, as erected by Davey, Paxman & Co., at St. Fargeau, Paris, for distributing air through the streets of Paris, for driving prime movers. The twelve air compressors are coupled directly on to the piston rods. Each engine is capable of working up to 400 horse power. The general design of this engine is the same as is illustrated and described on page 21 of this book. The whole plant has now been satisfactorily at work for several years.
THE "ECONOMIC" SAFETY BOILER.
The illustration on this page represents a battery of "Economic" safety boilers developing about 4,000 horse power for supplying steam to the compound condensing engines at St. Fargeau, Paris, before referred to in this work. This type of boiler was introduced by Mr. Paxman some thirty years ago, and it is one of the best steam generators before the public, not only for efficiency, but for durability and facility for repairs. It has (in the larger sizes) two flues emptying into a brick combustion chamber at the back of boiler, the gases then returning through the tubes and emptying themselves into a smoke box which conducts the gases to the flue made in the brickwork round the outside of boiler, or they can be led direct into the chimney without the brickwork at the sides. One great advantage is, that this brick combustion chamber is always red hot, and thus at the back of boiler provides for the perfect combustion of the gases, and there is little or no smoke. These boilers occupy less space, and cost considerably less for setting than the Lancashire type of boiler whilst they possess the advantages of this and the multitubular boiler combined. The gases are cut up and more equally distributed, and the temperature at the chimney is very much reduced beyond what can take place in a Lancashire or Cornish boiler; if only moderately worked, and provided the feed water is of good quality, the "Economic" boilers can be highly recommended. As will be seen from the illustration this boiler consists of a cylindrical shell, with one or two internal flues (according to size of boiler) and a number of smoke tubes running from end to end of the boiler. It is provided with Paxman's patent expansion boiler flue as per illustration, the form of which flue gives it such strength that thinner plates can be used in its construction than it would be safe to use in the plain flue. This is a great advantage, as it is a well-known fact that the heat passes more rapidly through thin plates, which are thus rendered more durable because they do not become overheated. In this way the full excellence of the material is retained for a great length of time. It is also well-known that the strength and durability of a boiler depends greatly upon there being proper provision made in its design for expansion or contraction. Where this is not provided for, furrowing and ripped seams are the inevitable result. Paxman's patent expansion boiler flue provides completely for this without injuring its efficiency as a stay. The flue is made up of a series of lengths as shown, which are made up of fine, soft, and exceedingly tough steel. The plates are bent in such a way as to be when finished, perfectly cylindrical, thus adding to the strength of the flue. They are then carefully welded. When welded, the ends are heated in a suitable furnace, and enlarged in a powerful flanging machine in such a way that the end of one plate exactly fits within that of the next; the holes are then drilled through both, and rivetting completes the work. It will be seen that both the laps, or doubling of the plate at the seam, as well as the rivet heads, are removed from the line of draught, and consequently escapes the scouring action of the gases as they pass along the flue. Flues made on this principle have withstood severe tests most successfully, and the collapsing strength is about double. Davey, Paxman and Co. have a very large and one of the most complete boiler works in the United Kingdom, fitted up with all the latest and approved machinery. They are also makers of Cornish, Lancashire, locomotive water tube, cross tube, marine, and also patentees and makers of the "Essex" patent vertical boilers, and also undertake any special boiler work for which they may receive enquiries. The boilers are constructed throughout by skilled workmen, aided by the most approved and modern machinery. The best materials only are used, and all boilers are tested by hydraulic pressure before leaving the works. The steel used is of a special mild quality, very ductile and easy to weld. It is manufactured expressly for Davey, Paxman and Co., and each plate is carefully annealed after having passed through the various machines. It is by giving such attention to the selection of material, good design and proportion, and general details of construction, that Davey, Paxman and Co. have attained the present high standing that they enjoy as one of the foremost firms in the engineering world.
Page updated: 05 APR 2005